Mini UZI

.22 LR Conversions for the Full Auto UZI

At least three different manufactures made .22 LR conversion kits for the full auto UZI: IMI, Group Industries (GI) and Vector Arms. FA kits from IMI are very uncommon and should not be confused with the more common semi auto kits from IMI. Group Industries made at least two versions of their FA kit. The early one has a bolt that looks a lot like a semi bolt with a separate striker unit inside the outer bolt. The later GI kit is a one piece aluminum bolt with fixed firing pin steel insert. Both of the GI kits came with a bolt, recoil spring, barrel and magazine. Vector copied (with permission) the later GI FA kit and further modified it. Vector had at least two variants in bolt style. Both styles came with a bolt, recoil spring, barrel and magazine. Vector is the only manufacturer that still sells FA .22 kits. Their kits seem to be the most reliable, although all .22 kits may require some "tuning" before they might work 100%. Everything has to be just right for them to function because the .22 round is difficult to make work in FA mode.

Magazines from the semi auto kits do not work with the FA kits, but GI magazines and Vector magazines are interchangeable. Barrels from the semi auto kits do not interchange with the FA kits.

For information on .22LR kit reliability and tuning, check out the excellent review by UZI Talk member Bob T. Following is a detailed look at each one of the different model .22 LR conversion kits and information on how they differ.

- Group Industries First Model
- Group Industries Second Model
- Group Industries Third Model
- Vector Arms Early Model
- Vector Arms Late Model
- Bolt Comparisons
- Magazine Comparisons
- Barrel Comparisons

Group Industries First Model
The early Group Industries .22 bolts were designed like the IMI semi auto bolts with a separate striker unit. The heavy, steel outer bolt moves only during cocking, not during firing. The striker unit catches on the sear via a connector rod on the left side of the bolt. (see ad for first model .22 kit)

Group Industries Second Model
The second model Group Industries was a more traditional style open bolt, making it easier to manufacture and more reliable. It still had a floating firing pin, which was activated by an "action bar". Firing pin components were inserted through an opening in the side of the bolt. Bolt body is aluminum. Steel plate on the left side catches the sear.

Details of the action bar and the firing pin block with cam. Upon firing, the action bar would hit the barrel before the bolt finished moving forward. The action bar would then strike the cam, which would push the firing pin forward as the bolt closed.

Group Industries Third Model

The third model Group Industries bolt was a further simplification of the firing mechanism. The third model switched from a floating firing pin to a fixed firing pin and no longer needed a hole cut in the side because of it.

Vector Arms Early Model

The early Vector kits were almost a direct copy of the GI kits. The bolt body appears to be made from GI second model bolts because of the hole in the side, but it has a fixed firing pin like the GI third model. The Vector bolts are slightly shorter than the original GI bolts.

Vector Arms Late Model
Changes from early model Vector Kit:
• Rear (left) end of the bolt is open on the bottom so it will not hit the 9mm ejector, which happened occasionally on the early Vector bolts.
• Steel plate on the side of the bolt is shorter and held on by one cap screw instead of two.
• Stiffer recoil spring that increases rate of fire.

Instructions for the Vector .22 kit

Bolt Comparisons

Four different .22LR bolts:
    • First model GI bolt. Steel outer bolt moves only during cocking. (See details of this bolt.)
    • Third model GI bolt. Aluminum bolt body configured like a tradition open bolt.
    • Early Vector bolt. Same design as the later GI bolt.
    • Later Vector bolt. Small design changes to improve reliability.

Left side view of five bolts:
• First model GI bolt. Connector on left side catches the sear.
• Second model GI Bolt. Aluminum body with steel plate where it catches the sear.
• Third model GI bolt. No cutout on side because it switched to a fixed firing pin.
• Early Vector bolt. Similar design to GI bolt but shorter.
• Later Vector bolt. Redesigned steel sear plate.

Close up of the steel insert in a later Vector bolt. The insert has a fixed firing pin on the front (for rim fire .22LR) and the extractor. The extractor fits into grooves on each side of the barrel. Also notice the back of the bolt is open on the bottom to guarantee that it will clear the 9mm ejector.

Comparison of second and third model GI bolts. The second model had a floating firing pin, which was activated by the action bar striking the barrel, which pushed it against a cam at the back of the firing pin.

Magazine Comparisons

.22 magazines consist of an original 9mm UZI magazine with an insert inside it to bring it down to .22LR size. The exact method of manufacturing the magazines has varied by vendor and over time.

This is an early design Group Industries 25 round magazine. The outer shell is a 25 round IMI 9mm magazine. The insert is aluminum, comprised of two halves held together at the top by the feed lip assembly. The top of the original IMI magazine is completely cut off and the insert is slid into the bottom of the magazine. A tab at the bottom of the insert fits into a cutout in the magazine body, keeping the insert from coming out the top.

An aluminum follow is slid into the bottom of the insert and then two magazine springs. The shorter spring is much stiffer than the long one. The floor plate has an additional hole drilled in it to catch the bottom of the magazine spring.

Three witness holes are drilled in the magazine body that align with holes in the insert so you can see how many rounds are loaded.

This is a later version of a Group Industries 25 round magazine. This magazine body is a South African contract mag but original IMI mags were used as well. The feed lips are welded to the magazine body rather than being part of the insert like they were in the earlier version. It's unclear if this simplified production or if it was done to improve reliability.

It uses the same aluminum follower, dual spring system and floor plate as the early version. The magazine body and aluminum insert have only one witness hole rather than three like the earlier version.

The latest Vector magazines are available in 20 and 28 rounds. They have a plastic insert (bottom left of photo), a plastic follower and a single magazine spring.

Magazine followers (left to right):
    • Early GI magazine. Feed lips are part of the insert and are short. Front of aluminum follower is square.
    • Later GI Magazine. Feed lips are welded to mag body and are longer. Front of aluminum follower is rounded.
    • Early Vector magazine. Design is virtually identical to late GI mags.
    • Later Vector Magazine. Feed lips similar but now integrated with the side of the mag body. Plastic follower and insert.

Barrel Comparisons

Four different barrel styles:
    • Earlier GI barrel. Barrel bands are cut so it fits in a semi trunion. Chamber area reduced for semi feed ramp.
    • Later GI barrel. Extractor groove cut longer.
    • Earlier Vector barrel.
    • Later Vector barrel. The chamber area is reduced to fit in a full auto gun with a semi feed ramp.

Four different feed ramp styles:
    • Early GI barrel. The barrel diameter around the chamber area is reduced so it will fit in a semi feed ramp.
    • Later GI barrel configured for full auto feed ramp. Nicely shaped feed ramp.
    • Earlier Vector barrel configured for full auto feed ramp.
    • Later Vector barrel configured for semi feed ramp gun. The .22 feed ramp area is widened to make feeding more reliable.

A view of the chamber end of the barrel inserted into the gun shows how it sits on top of the 9mm feed ramp. Because of that, the barrel diameter must be reduced on the chamber end to make room for the 9mm semi ramp - even on a full auto gun that doesn't have the full restrictor ring.

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